[pgrouting-dev] Fixes for Bidirectional code just checked in

[Stephen Woodbridge]

On 6/4/2013 3:53 PM, Alec Gosse wrote:
> Hello,
>
> I've just pulled from the develop branch and built fresh and I'm
> getting a server crash from pgr_bdastar. If I run exactly the same
> thing using pgr_astar, it works. This is using postgres 9.2.4 and
> postgis 2.0.3 from Homebrew on Mac 10.8.3

I'm using pg9.2.4 and postgis 2.0.x or 2.1.0beta3dev and I fixed these 
issues I thought. Evidently not.

> I'm still working on a bulk routing function using bdastar, but just
> realized that the regular version was crashing without my
> modifications. I'm happy to try to track this down, but have little
> knowledge of how to debug within postgresql. Any pointers would be
> appreciated.

OK, start by uncommenting #define DEBUG 1 in both the C and C++ code. 
Then add more DBG('I got here message\n"). In the C++ code these 
messages get written to a file '/tmp/sew-debug' and you can do a tail -f 
on that in another window to see your progress.

This is likely a issue in the C++ code but it may also be something 
systemic about the way we are integrating code. If you build your own 
postgresql you might want to rebuild it with --enable-cassert option to 
configure which will put the database backend into a more rigorous 
memory check mode.

That is a start, I would be appy to help more if I can.

Thanks,
   -Steve

> Best, Alec
>
>
>
>
> On Jun 1, 2013, at 2:13 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com> wrote:
>
>> Hi all,
>>
>> I think I have just submitted changes to the bidirectional dijkstra
>> and astar routines the resolve the server crashes we were seeing.
>> This closes on major outstanding bug against 2.0.
>>
>> Razequl,
>>
>> I made two simple changes to your code BiDirDijkstra.cpp and the
>> astar version:
>>
>> 1. in BiDirDijkstra::initall I add: m_vecNodeVector.reserve(maxNode
>> + 1);
>>
>> 2. in BiDirDijkstra::bidir_dijkstra I move the call to
>> initall(maxNode); to before construct_graph(edges, edge_count,
>> maxNode);
>>
>> This does two major things:
>>
>> 1. std::vector doubles the size of the array every time it needs to
>> increase its size and then needs to copy the old data to the new
>> area.
>>
>> 2. reserve() pre allocates all the memory we need once, which avoid
>> realloc memory fragmentation and avoids the copy each time it
>> reallocs so this improves performance.
>>
>> Anytime you know how much space you are going to need you should
>> reserve it up front.
>>
>> So things look good for now.
>>
>> Thanks, -Steve _______________________________________________
>> pgrouting-dev mailing list pgrouting-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/pgrouting-dev
>
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